Assessment of the renal circulation during pregnancy with color Doppler ultrasonography.
OBJECTIVES: A non-invasive method of assessing the renal vasculature during pregnancy would be useful in the management of patients with renal dysfunction resulting from preeclampsia or chronic renal disease. The objectives of this study were to determine (1) whether color ultrasonography during pregnancy facilitates Doppler interrogation of renal and intrarenal arteries, allowing (2) the assessment of differences between waveforms from nonpregnant and pregnant women and (3) the analysis of waveform variability throughout the kidney and between the right and left kidneys. STUDY DESIGN: In a cross-sectional study renal and intrarenal artery flow waveforms were obtained from women in early (12 to 19 weeks; n = 8), mid (20 to 29 weeks; n = 11), and late (30 to 37 weeks; n = 14) pregnancy with eight age-matched, nonpregnant women acting as controls. Waveforms were analyzed for pulsatility index, resistive index, and systolic/diastolic ratio. RESULTS: Left or right renal and upper- and lower-pole interlobar artery waveforms were obtained from all women. The mean pulsatility index values for the nonpregnant women were not significantly different from those women in early, mid, or late pregnancy. In the nonpregnant women, the left renal artery pulsatility index (1.13 +/- 0.13) was greater than the left lower interlobular artery pulsatility index (0.91 +/- 0.08; p < 0.05). During pregnancy renal and interlobar artery pulsatility index values were greater than those for the corresponding interlobular arteries, but the differences were not significant. Mean renal and intrarenal artery pulsatility index values were greater on the right, but the difference was significant only for the lower interlobular artery in midpregnancy. CONCLUSIONS: Pregnancy does not significantly affect renal and intrarenal artery flow waveforms, nor are there significant differences between waveforms from the renal and interlobar arteries.